#36714: Async signals lose ContextVar state due to use of asyncio.gather
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Reporter: Mykhailo Havelia | Owner: (none)
Type: Bug | Status: new
Component: HTTP handling | Version: dev
Severity: Normal | Resolution:
Keywords: asyncio, signals | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Mykhailo Havelia):
Replying to [comment:8 Carlton Gibson]:
> I reviewed #36315 and marked it as Ready for checkin, so hopefully that
can progress to clear the path for work here.
>
Test MR: https://github.com/Arfey/django/pull/3/files
I used the latest changes and prepared a fix for context sharing. At this
point, we have:
- Successful context sharing between async handlers for asend/send
- Successful context sharing between sync handlers for asend/send
- Successful cross-sharing between async/sync handlers for send
Current issue:
- Cross-sharing between async/sync handlers for asend
The difference is in how send and asend execute handlers. `send` runs sync
handlers first, and then runs async handlers in parallel and this works
fine. `asend` tries to run all handlers "in parallel". In this case,
`sync_to_async` copies the context instead of using the existing one, so
context sharing breaks. I propose splitting the execution of sync and
async handlers for asend as well.
Current code:
{{{
await _gather(
sync_send(),
_gather(
*(
receiver(signal=self, sender=sender, **named)
for receiver in async_receivers
)
),
)
}}}
Proposed adjustment:
{{{
await sync_send()
await _gather(
*(
receiver(signal=self, sender=sender, **named)
for receiver in async_receivers
)
)
}}}
What do you think?
--
Ticket URL: <https://code.djangoproject.com/ticket/36714#comment:9>
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